Stencil sheet



Patented Apr. 7, 1931 PATENT OFFICE SHINJIRO HORII, F TOKYO, .mimn

STENCIL SHEET No Drawing.

My invention relates to improvements in stencil sheets for, use in duplicating manuscript, typewriting, drawings and the like, consisting of a sheet of fibrous material provided with a coating of an ink-resisting composition.

Heretofore, such stencil sheets have been made of a fibrous basecoated with a composition, such as comprising (1) coagulated protein and substances increasing. the plasticity of the protein, such as resins, fatty acids, hydrocarbons and fatty substances, (2) a colloid, such as gelatine and Irish moss, glycerine and monopole soap, (8) a gelatinous organic colloid dispersable in an aqueous medium and an oily or waxy constituent consisting Wholly or mainly of the tempering agent or the organic colloid, (4.)

a colloidal substance, as gelatine, Turkey-red oil, a fatty acid, such as oleic and palmitic acid, and a coagulant, (5) a colloid dispersed in water'and an emulsifying agent comprising a starch sulfonated oil mixture and a. tempering agent, including japan and paraffin wax, and (6) acase in solution emulsified with oils or fats of mineral animal or vegetable nature.

According to the present invention the coating material comprises a gelatinous organic colloid dispersed in water in accordance with naphthenic acids acting as a tempering agent.

Naphthenic acids preferably used in the invention may be separated from petroleum distillates and are purified. The purified naphthenic acids are very stable and the viscosity is less affectedby the changes of temperature, and they do not possess the properties of the unsaturated fatty acids of the oleic series. They do not become sticky on exposure to the air and'showa comparatively weak acidity.

In this connection it may be remarked that the employment of naphthenic acids in association with esters of polysaccharides dis- Application filed April 30,

1929. Serial No. 359,429.

solved in volatile solvents has been proposed in the production of stencil sheets as indicated in my U. S. Patent No. 1,594,525 issued Aug. 3, 1926. It has been found, however, that the employment of the volatile solvents makes the manufacture expensive and also particularly dangerous. According to the present invention, organic colloids dispersable in water are used as the main component of the ink-resisting medium, instead of the esters of polysaccharides. The prepared stencil sheets are very durable and stable without the drawback of becoming sticky or rancid on being kept as is the case where fatty oils,fats' or fatty acids are used. Also, the stencil sheets are more soft and pliable than those produced in accordance with my original invention, giving clearer stencils by the pressure of the type of a typewriting machine. Moreover, the stencil sheets are not injurious to the metal parts of the typewriting machine because of the feebler acidity of naphthenic acids as compared with fatty acids or sulfonated oils.

In the practice of the invention, a coating material is prepared by an organic colloid, such as gelatine, being dissolved in sufficient quantity of water, and then being emulsified with a mixture of naphthenic acids and aqua ammonia. Then the solution is applied to a fibrous base, such as Japanese yoshino paper,

,in a suitable manner. After the water and ammonia have been expelled, the stencil sheets are ready for use. In this case, the coating of the stencil sheet consists of the organic s0 colloid dispersed in naphthenic acids. If desired, a tempering agent such as hydrocarbon oils, fatty oils, fats, waxes, fatty acids and naphthenic acid glycerides or other naphthenic acid esters, such as glycols (e. g. ethyl: 85. ene glycol), and mono-alcohol (e. g. methyl, ethyl, pro'pyl, or amyl alcohol) esters may be incorporated with the naphthenic acids forming a complete emulsion. Also, a coagulant for the organic colloid, such as potassium dichromate or formalin, and suitable coloring material such as dyes or pigments, may be added to the above coating material. The composition may also be added to the paper stuff in a mixing hollander during the paper making operation.

The proportions of the ingredients may vary according to various circumstances. By way of example, the following proportion can be used Parts by weight Gelatine Potassium dichromate 0.1 Blane fixe 10 Water 95 Naphthenic acids 15 Aqua ammonia 5 Licinoleic acid 5 Castor oil 5 Japan wax 2 The composition is uniformly mixed and is diluted to a suitable viscosity.

What I claim is 1. A stencil sheet comprising a base of fibrous material coated with a composition consisting of a gelatinous organic colloid dispersed in water in admixture with naphthenic acids.

2. A stencil sheet comprising a base of fibrous material coated with a composition consisting of a gelatinous organic colloid dispersed in water, in admixture with naphthenic acids and waxy material.

In testimony whereof I aflix my si nature.

SHINJIRO H RII. 

